Edit, 14th october 2007: this article follows the review of the original THRESHOLD T2 preamplifier, which can be found here on our site. We recommand you to first read the original review.

As previously said, one of our reference preamplifiers, the THRESHOLD T2 , has been upgraded. After more than 10 years of good service, it became necessary to change some parts that normally decline as time passes (this is the case for the capacitors for exemple).
Its musicality was still extremely good, but we suspected that some improvement was possible.
It is now back to home, and the first feedback is herebelow.

The diagnosis:

Upgrading or replacing parts on any high end component is not something you should try without serious skills in electronic: replacing parts already requires some expertise, but you should not modify the circuit unless taking the risk to loose the qualities and musicality of the original design.
Therefore, it was logical for us to ask FIDETECH to proceed with such a work, with the main objective being to put the T2 back to the Manufacturer specifications (at least).

The diagnosis was that some parts were too used (such as some capacitors) both in the Power Supply and in the preamp circuits.
The work done by FIDETECH is superb, both mechanically and from an electronic viewpoint. To convince you, just have a look at the photos of the Power Supply before and after the upgrade:

the original Power Supply

the upgraded Power Supply, with "E.P.O inside"...

It is obvious that a serious work has been done, and that some "amphetamins" have been added to the original Power Supply., which was already oversized fro a preamp: we remind you that the original Power Supply hosts a 150VA transformer and 70.000µF of capacitance....

The main modifications are:

the 2 active components, referenced TOSHIBA 2SA1302 and 2SC3281 have been changed by new ones (made in Japan).

the 6 big capacitors ELNA, made in Taïwan..., 4x10.000µF/63V/85°C and 2x15.000µF/36V/85°C have been replaced by B.H.C. Aluminium capacitors having a better quality, and made in Europe (United Kingdom). They have the same value, but they are much bigger with screw based contacts, in order to allow a high current possibility (they are rated 11A). The power suplu is entirely filled, it was impossible to put bigger caps in the box...

4 small capacitors have been added in // with the big ones. They are VISHAY 0.47µF/630V/85°C. This is done in order to improve the filtering in the high frequencies and the dynamic range. These capacitors are the same ones than FIDETECH added on the upgraded SA/3.9e power amplifier: look here.

The quality of the work is excellent: the T2 looks like if it just goes out from the factory. Everything is perfectly done, and there is clearly a serious study of the parts implementation, the B.H.C. capacitors and the small VISHAY entirely filling the box.

The parts that were changed in the preamp itself.

A lot of parts were changed in the preamp itself: many capacitors, transistors, etc.... Here is the photo of the parts replaced:

Photo of the parts that were replaced

Parts changed in the Power Supply:

1,2 and 3: original capacitors (made in Taiwan) of the Power Supply, 4 x ELNA 10.000µF/63V/85°C and 2 x ELNA 15.000µF/36V/85°C, replaced by B.H.C. made in the United Kingdom.

Parts changed in the Preamp itself:

4: 6 x ELNA capacitors 220µF/25V/85°C changed by 105°C

5: 18 x ELNA capacitors 47µF/50V/85°C changed by 105°C

6: 10 x C4793 replaced by new ones

7: 4 x ELNA capacitors 2200µF/50V/85°C replaced by 105°C

8: 8 x A1360 replaced by new ones

9: 10 x A1837 replaced by new ones

10: N630 NPS A42 and N548 NPS A92 replaced by new ones

11: 4 x A1145 replaced by new ones

12: internal onboard LED

13: 4 x C2705 replaced by new ones

As you can see, the T2 has been seriously regenerated... You can locate where some parts were changed by looking at the following photo:

Photo of a few changed parts

Here is a photo of the internal preamp stages:

The internal Threshold T2 preamp stages

as well as a global view of the preamp circuits, where you can see that the LCD display and volume control are isolated from the line stages (and dust) by a Copper (Cu) protection cover at the bottom of the image:

The global internal view of the Threshold T2 preamp

Here is a photo of a 105°C new capacitor:

What are the results from a musical viewpoint ?

This is obviously the most important, and as we said previously, the preamp is currently in its burning in period, so the parts have not yet reached their maximum performance.

I probably have the T2 service manual somewhere in my house but I am away until new year: please post a request our Forum or send me a private mail from our Forum, and I will check what I have when I am back. All the best,

Reaction #5

by Willem 02/12/2012 @ 17:25

As a happy owner of a Threshold T2 I read the upgrade article with great interest. Because of it's age and a light (white?) noise in one of the channels, I'm thinking of changing some parts.But a closer look at the shown photos in this article tells me that there is more than one version of the T2. The channel boards in my T2 are slightly different and also the mentioned components (e.i. the larger transistors) are from another type. The power supply of my T2 only has 5 large elcos of the same type instead of the 4 and 2 on the photos in this article.Can anyone help me with a technical schematic of this T2

This T2 preamp is no longer manufactured, so you can only buy a second hand model. In addition, be aware that this upgraded version has been done on a specific request and has never been manufactured by Threshold. So if you plan to get it, you have First to buy a used regular T2 preamp, and Secondly to have it upgraded by a qualified technician (a very qualified technician...).

Feel free to contact me directly if you have any question,Nounours

Reaction #3

by ampseeker21 19/05/2011 @ 20:54

Thank you for the excellent and detailed review. I have been looking through a series of amps for ones that meet my specific requirements and I think you have reassured my original feeling towards this specific model. If one was to want to purchase this amp would it be available online only, or could it possible be found at electronics retailers such as hh gregg?

I understand (and accept) your doubt: there are tons of discussions about the improvement/no improvement regarding these kinds of upgrades. And these discussions will probably never be finished...I have just tried to give an honest feedback of my listening experience...